In most cases, the language mode can be inferred from the closure and
the context. Computing the language mode instead of passing it around
simplifies the ICs and will make it possible to go towards lazily
allocating feedback vectors. Currently ICs obtain the language mode from
the feedback vectors and with lazy feedback allocation we may not always
have feedback vectors. Since computing language mode is a bit expensive
we want to defer it as far as possible.

In Array builtins and other builtins like Reflect.Set we need to force a
language mode when setting the properties. To support these cases the
SetProperty methods allow the language mode to be overridden when needed.

This is a first cl in a series of cls, that will defer the language mode
computation further and remove language mode where it is not needed.

BUG: v8:8580
Change-Id: I9c2396e3bcfe77c3c9d6760c46d86954d54744b9
Reviewed-on: https://chromium-review.googlesource.com/c/1409426Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58893}